<h1>字符函数 - isalpha</h1>
<p>原型：extern int isalpha(int c);</p>  
<p>用法：#include &lt;ctype.h></p>
<p>功能：判断字符c是否为英文字母</p>
<p>说明：当c为英文字母a-z或A-Z时，返回非零值，否则返回零</p>

举例：
<pre><code class="language-c">
    // isalpha.c
    
    #include &lt;syslib.h>
    #include &lt;ctype.h>
    #include &lt;stdio.h>

    main()
    {
      int c;
      
      clrscr();        // clear screen
      printf("Press a key");
      for(;;)
      {
        c=getchar();
        clrscr();
        printf("%c: %s letter",c,isalpha(c)?"is":"not");
      }
      return 0;	// just to avoid warnings by compiler
    }
</code></pre>  
相关函数：<a href="isalnum.html">isalnum</a>,<a href="isdigit.html">isdigit</a>,<a href="isxdigit.html">isxdigit</a>,<a href="iscntrl.html">iscntrl</a>,<a href="isgraph.html">isgraph</a>,<a href="isprint.html">isprint</a>,<a href="ispunct.html">ispunct</a>,<a href=isspace.html">isspace</a>

